Solution to diminished AC performance after evaporator core replacement

[GOLDCYLON]

Many thanks to Vettemed, I have created this thread to be a standalone thread as a searchable solution. Folks take note of Andrews post #318 in his update of his hi miler ZR-1 project. If you are having dimished AC performance after replacing the evaporator core. Last summer my car in my opinion was not cooling down as much as it used to do in heavy AC load conditions in the 118-122 dog days of summer in Arizona. It always used to be a lot colder from my memory and since reparing the AC a year or so ago with all new parts I just could not figure out what was going on. I remembered this post up as Andrew was having the same problems. I put this on the long list of projects I wanted to complete this winter. I missed it.. however, and it didnt make it to the list last winter, Tuesday of this week was a uber rare Santa Ana winds fed blustery day here in AZ and the evening temps in the garage were in the 70s and I said well... now or never. I had my evaporator core replaced while I was TDY at work so I never saw the original unit that was removed. Long story short I had the exact same gap on the left side of the heater core that Andrew has pictured in picture #1 of post #318. So I fed gray foam material, the kind used used to protect guns and hard drives into that vertical slot. Walla.. in 100 degree temps yesterday the AC was spitting out 46 Degree air.
http://i680.photobucket.com/albums/vv163/agchoset/IMG_0469.jpg
This view is what you might see if you pull the blower motor and look towards the evaporator core. See that vertical gap? it should not be there. As Andrew stated in his post either the replacement evaporator core is shorter than stock or it is factory foamed in on that side. Make sure you or your installer is aware of this issue so they can address it at time of replacement. Andrew was 100% correct with the gap hot air was bypassed into the system and mixing into the cooler air.

[VetteMed]

Daryll, good idea to make this more easily searchable. However, one correction, this is the evaporator core, not the heater core. :)

[GOLDCYLON]

Daryll, good idea to make this more easily searchable. However, one correction, this is the evaporator core, not the heater core. :)


Duh I knew that lol and I updated it. Wish you had your car back bro

[mike100]

Airflow from small pressure differentials is an amazing phenomenon. So many air-cooled VW's back in the day ran hot from a bad engine seal separating the top half from the bottom which allowed for the cool air to be ducted to the cylinder fins etc.

Also same deal on some air cooled electric motor drives we used to make. You can just about double the useful cfm through a heat exchanger with the leaks eliminated.

[VetteMed]

Duh I knew that lol and I updated it. Wish you had your car back bro

Maybe someday it'll pop up for sale again...

[Dynomite]

Daryll, good idea to make this more easily searchable. However, one correction, this is the evaporator core, not the heater core. :)

This is what got Daryll's attention Solution to Evaporator Core Leaks (http://www.zr1.net/forum/showthread.php?p=144810)

This has now been "linked" in -Solutions- (http://www.zr1.net/forum/showthread.php?t=16778) (Air Conditioner and Heater) ;)

[GOLDCYLON]

POSTING THIS UP again as we are in the dog days of summer again ! GC

[Subfixer]

That is the gap I was explaining in the other post about fan speed.
The original seal fills that gap.
Since the seal is glued to the evaporator, many get tossed (and not replaced) by unknowing techs.
Also missing in the photo is the debris screen that sits between the fan and evaporator.

[Erik]

POSTING THIS UP again as we are in the dog days of summer again ! GC

Thank you, sir! Very useful info.

[GOLDCYLON]

That is the gap I was explaining in the other post about fan speed.
The original seal fills that gap.
Since the seal is glued to the evaporator, many get tossed (and not replaced) by unknowing techs.
Also missing in the photo is the debris screen that sits between the fan and evaporator.

Yep gotta pic of the Debris screen sub fixer ? I have had 3 heater cores replaced in 3 different C4s. Nine of em Had a screen and all had that damn gap. Leaves me to believe all three were replaced once before they came into my care.

[Subfixer]

Yep gotta pic of the Debris screen sub fixer ? I have had 3 heater cores replaced in 3 different C4s. Nine of em Had a screen and all had that damn gap. Leaves me to believe all three were replaced once before they came into my care.

I'll try to pull the blower fan this weekend and see if I can get a good pic.

[GOLDCYLON]

I'll try to pull the blower fan this weekend and see if I can get a good pic.

Oh no don?t do that just to take pic!!!! :cheers:

[Subfixer]

Maybe I was imagining the screen.....
I could swear my unmolested 92 had a screen between the blower fan and evaporator.
I scoured the internet looking for pics, but could not find an example.

Anyway, here's an extreme example of a clogged evaporator.
https://www.corvetteforum.com/forums/c4-tech-performance/3697866-clogged-evaporator-before-and-after.html

Not a lot of air flow before cleaning.
Mine was only halfway clogged on the bottom half @ 20,000 miles.

[Subfixer]

If anyone needs a new evaporator, these guys make them with the correct bend in the bottom tube for ZR1. They make them per order. Excellent workmanship.

This is an example of what I used in my 92, converted to 94-95 R134a system.

https://www.oldairproducts.com/product/evaporator-coil-gm-chevrolet-corvette-w-j-eng-94-95-10-6793/Default.aspx?gfid=p117435-c117622&source=googleshopping&source=googleshopping&adnetwork=u&adtag1=&adtag2=&adcreative=358544127295&adposition=&admatchtype=&adkeyword=&gclid=EAIaIQobChMI_fvi0L3u6gIV-AiICR07LQ5fEAQYAiABEgKz9_D_BwE

[GOLDCYLON]

I repost this from time to time. GC :cheers:

[HAWAIIZR-1]

I repost this from time to time. GC :cheers:



Thank you Daryll! I have never seen this post before.


Sent from my iPhone using ZR-1 Net Registry (http://r.tapatalk.com/byo?rid=90383)

[GOLDCYLON]

Thank you Daryll! I have never seen this post before.


Sent from my iPhone using ZR-1 Net Registry (http://r.tapatalk.com/byo?rid=90383)

You're welcome Craig. It's and oldie but a goodie :cheers:

[HAWAIIZR-1]

You're welcome Craig. It's and oldie but a goodie :cheers:

GC,
I?ll do it all one time when I replace the heater core and upgrade the wiring and alternator since I have the spal fans now and upgrading the stereo a little. Man, those spal fans let you know when they are on! 😆 I finally drove it today since the install. :cheers:

[GOLDCYLON]

GC,
I?ll do it all one time when I replace the heater core and upgrade the wiring and alternator since I have the spal fans now and upgrading the stereo a little. Man, those spal fans let you know when they are on! 😆 I finally drove it today since the install. :cheers:

Embrace the spal rpmish Craig

[HAWAIIZR-1]

Embrace the spal rpmish Craig

Fer sure. It cools it down quick. I think they improved the shroud and seal to radiator so it works great. My highest temp was 209 all day but only 90 degrees outside. I?m happy!!